Occurrence and bioaccumulation of polybrominated diphenyl ethers in sediments and paddy ecosystems of Liaohe River Basin, northeast China

Concentrations of 16 polybrominated diphenyl ether(PBDE) congeners were measured in river sediments, paddy soils and three species of paddy-field organisms(crab, loach and carp) collected from the Liaohe River Basin, northeastern China. The total contents of PBDEs(∑_(16)PBDEs) in sediments and paddy soils were in the ranges of 273.4–3246.3 pg/g dry weight(dw), and 192.1–1783.8 pg/g dw, respectively. BDE 209 was the dominant congener both in sediments and paddy soils. The concentrations of ∑_(16)PBDEs in sediments were significantly higher than those in the adjacent paddy soils, indicating a potential transport of PBDEs from river to paddy ecosystems via river water irrigation. The biota–soil accumulation factor(BSAF) was calculated as the ratio between the lipid-normalized concentration in paddyfield organisms and the total organic carbon-normalized concentration in paddy soil. The average BSAF values of ∑15PBDEs followed the sequence of crab(3.6) loach(3.3) carp(2.1). BDE 154 had the highest BSAF value, and a parabolic trend between BSAF values of individual PBDE congeners and their log KOWvalues was observed. In view of the fact that crab had the larger BSAF value and higher lipid content, the ecological risk and health risk for crab cultivation in paddy fields should be of particular concern.     

泽龙湖景观水污染治理及生态修复

为了去除泽龙湖微污染景观水中的氮、磷及有机物等污染成分,采用人工增氧和浮田型生态岛技术对泽龙湖景观水进行了生态修复。结果表明,人工增氧能很好地氧化水中有机物,生态岛水生植物可有效地吸收氮和磷,处理后湖水可达到《地面水环境质量标准》(GB 3838—2002)中的Ⅳ类标准。     

基于稳态与非稳态的喷吹管内流场的对比研究

针对等孔径喷吹管,利用CFD软件对其内流场进行数值模拟,得到不同入口流量条件下的流场分布特性。对喷吹管进行非稳态流场模拟,并与稳态模拟结果分析比较,模拟结果误差控制在1%以内,验证了将喷吹管非稳态内流场简化为稳态流场分析具有一定的可行性。沿着喷吹管气流流动方向,喷嘴出口流量分布不均匀,整体有增大的趋势;沿喷吹管轴向气流渐趋均匀,即越靠近端面,喷吹偏心角越小,甚至为0。     

水稻田非点源污染原位试验研究

为了研究野外水稻田的非点源污染,本试验采取一种新的原位观测方法:即在不改变水稻田原有出流特征前提下,在水稻生长季采集田面水水位和降雨信息,通过水位变化曲线计算水稻田每日的蒸散发和渗漏损失量,再根据水量平衡关系计算径流量.观测期间定期采集田面水测定总氮(TN)、总磷(TP)浓度,根据径流量和浓度估算非点源污染流出负荷量.试验选取北京市海淀区上庄镇某村水稻田试验田块,通过1年的试验观测得到在生长季内的37场降雨中共有9场降雨产生了出流.另外,还有2次人工排水和1次农田回归流形成了非点源污染.经计算试验区水稻田每个生长季TN输出系数为8.8 kg·hm-2,TP输出系数为0.47 kg·hm-2.该观测方法针对具有多出水口且最低田埂高度动态变化的野外水稻田的非点源污染观测具有较强的可操作性.     

废弃物施加对福州平原稻田土壤团聚体分布及其稳定性的影响

为了阐明废弃物施加对稻田土壤团聚体分布及其稳定性的影响,以福州平原稻田为研究对象,对对照、石膏、贝壳、生物炭和炉渣5种处理样地0~10 cm、10~20 cm、20~30 cm土层土壤团聚体分布及其稳定性,包括0.25 mm团聚体含量(DR0.25)、平均质量直径(MWD)、几何平均直径(GMD)、分形维数(D)进行了测定和分析.结果表明,与对照样地相比,石膏、贝壳、生物炭和炉渣施加后均增加了土壤团聚体DR0.25、MWD和GMD值,其中,石膏施加后土壤团聚体DR0.25、MWD和GMD值分别增加了12.76%、12.13%和12.17%,贝壳施加后分别增加了32.65%、31.83%和33.86%,生物炭施加后分别增加了12.07%、9.32%和11.70%,炉渣施加后分别增加了19.70%、13.59%和18.10%,但与对照样地相比,石膏、贝壳、生物炭和炉渣施加后土壤团聚体分形维数均表现为减小的趋势,分别减小了4.02%、11.65%、4.37%、9.29%.从土壤团聚体DR0.25、MWD、GMD值和分形维数的变化特征来看,石膏、贝壳、生物炭和炉渣施加均提高了土壤团聚体的稳定性.     

Integrating Temporal Inequality into Conservation Planning to Improve Practice Design and Efficacy

In contrast to spatial inequality, there are currently no methods for leveraging information on temporal inequality to improve conservation efficacy. The objective of this study was to use Lorenz curves to quantify temporal inequality in surface runoff and tile drainage, identify controls on nutrient loading in these flowpaths, and develop design flows for structural conservation practices. Surface runoff (n = 94 site‐years) and tile drainage (n = 90 site‐years) were monitored on 40 fields in Ohio. Results showed, on average, 80% of nitrate‐nitrogen, soluble reactive phosphorus (P), and total P loads occurred between 7 and 12 days per year in surface runoff and between 32 and 58 days per year in tile drainage. Similar temporal inequality between discharge and load provided evidence that loading was transport‐limited and highlighted the critical role hydrologic connectivity plays in nutrient delivery from tile‐drained fields. Design flow criterion for sizing structural practices based on load reduction goals was developed by combining Lorenz curves and flow duration curves. Comparing temporal inequality between fields and the Maumee River, the largest tributary to the western Lake Erie Basin, revealed challenges associated with achieving watershed load reduction goals with field‐scale conservation. In‐field (i.e., improved nutrient and water management), edge‐of‐field (i.e., structural practices), and instream practices will all be required to meet nutrient reduction goals from tile‐drained watersheds.     

Assessment of Physical Load at Work Sites: A Finnish–German Concept

The aim of this article is to introduce a set of work physiology methods for the assessment of physical load at the work site and to consider (a) their relevance for different types of muscular work, and (b) their feasibility for occupational health and safety practitioners. The results of an ergonomic intervention study for the reduction of workload associated with various manual materials handling tasks were used for the evaluation of the feasibility and sensitivity of the measurements of heart rate, the Edholm and OWAS methods, and the ratings of overall and local perceived exertion. The methods proved feasible, although time consuming, and their sensitivity for the quantification of small changes in physical workload was limited. Despite these shortcomings, these methods can be used by occupational health and safety practitioners when their strategy and data collection techniques are developed further. In conclusion, there are relevant and feasible methods fora reliable work-site assessment of cardiorespiratory and postural load related to the activation of large muscle masses. On the other hand, field methods for the quantification of local static workload and repetitive type of workload with small muscle masses are scarce.     

微直流电场对大肠杆菌生长代谢活性的作用

对大肠杆菌（Escherichia coli,DH5α）培养液在连续培养时分别通入不同强度的直流电场,研究了其在持续直流电刺激下的生长曲线、pH曲线、ATP酶活性、胞内总蛋白含量、细胞膜通透性以及细菌微观形态变化.结果表明,适宜的直流电能够促进大肠杆菌增殖;大肠杆菌的ATP酶活在25 mA电流作用下在对数生长前期、对数...     

Deposition Velocities of SO2 and O3 over Agricultural and Forest Ecosystems

The results of field studies that measured the flux anddeposition velocity of SO₂ and O₃ are reported. Three of the studies were over agricultural crops (pasture, corn, and soybean), and two were over forest (a deciduous forest and a mixed coniferous–deciduous forest). In all cases the deposition velocity for SO₂ was higher than that for O₃. Diurnal cycles of SO₂ deposition velocity were similar in shape, but not magnitude for all surfaces; however those for O₃ showed some difference between forest sites where the peak was in the morning, and the agricultural sites where the peak occurred at mid-day. Seasonal cycles of SO₂ were affected by deposition to surfaces when leaves were not active, yet surface conductance is significant, but not for O₃ where stomatal uptake is the primary pathway for deposition.(On assignment to the National Exposure Research Lab., US EPA) (e-mail:     

非均匀电场对土壤中基因工程菌的迁移与机理

以克隆有绿色荧光蛋白基因的Rm1021-GFP细菌作为标记细菌,研究了该细菌在非均匀电场作用下在土壤中的运移特征和存活性,分析了其运移机理和影响因素.结果表明,非均匀电场能有效地促进土壤中Rm1021-GFP细菌的运移,电泳、介电泳和随电渗析流迁移是其主要机理,土壤介质、电压梯度和电极反应是其主要影响因素,电极反应对电极附近细菌的存活性有不利影响.